1. Field of the Invention
The present invention relates to a method and apparatus for mounting an accessory on a machine tool and, in particular, to a method and apparatus for automatically mounting a right angle milling head to a horizontal boring machine.
2. Description of the Invention Background
For decades, all large metal machining operations have employed the services of horizontal boring machines. Such apparatuses are aptly named because they provide a horizontal shaft on which either milling, facing, drilling or other tools may be received. The horizontal shaft is typically mounted within a vertically displaceable housing while the workpiece is mounted on a table or carriage which may be moved along both horizontal axes relative to the housing. However, because the axis of the tool is fixed in the horizontal plane, work may only be performed on limited surfaces of the workpiece.
In order to increase the productivity of horizontal milling machines, those in the art have developed what is commonly referred to as a right angle head as an attachment to the horizontal boring machine. A right angle head is attached to the housing and is powered by the horizontal shaft of the apparatus. As its name would suggest, the right angle head serves to allow the rotary motion to be imparted along an axis which is perpendicular to that of the horizontal shaft. A tool receiving spindle similar to that provided on the horizontal boring machine is provided on the right angle head. Accordingly, by the use of the right angle head, machining such as milling, boring or facing operations may be performed along the horizontal axis which is perpendicular to that of the horizontal shaft and the overall utility of a horizontal boring machine may be markedly increased.
However, the prior art methods of attaching and readying the right angle head for use have been exceedingly inefficient. According to the prior art methods, the right angle head is prepared for attachment to the horizontal boring machine by first lifting the right angle head with a crane which must be provided by the machine shop itself. After lifting the right angle head in proximity to the housing, the operator must carefully align the bolts provided on the right angle head with the corresponding bolt holes on the housing. Because the right angle milling head weighs several hundred pounds, the alignment of these holes is very difficult at best and, at worst, damaging to the right angle head and the housing. Once the holes are aligned, the right angle head must be bolted to the housing and the bolts, if they are not lost, must be tightened to the appropriate torque. Now the arduous task of aligning the right angle head to the requisite tolerances of less than one-thousandth of an inch must transpire. The right angle head is mounted on an extended coupling to displace it from the housing. An alignment plate is then attached to the right angle head and then the bolts which attach the right angle head to the coupling must be carefully adjusted while continuously citing off the alignment plate until the requisite alignment is achieved. Finally, the alignment plate must be removed and the tool inserted into the spindle on the right angle head.
As is apparent from the foregoing, the attachment and alignment of the right angle head, according to prior art practices, often requires in excess of three hours' time. It will be readily appreciated that the loss of utilization of the horizontal boring machine, whose capital cost may exceed $1,000,000, coupled with the loss of operator time to effect the attachment of the right angle milling head, yield significant losses of productivity and expense. In accordance with the present invention, however, apparatus is provided for automatically attaching the right angle head with improved accuracy and in a time of less than five minutes. As such, the shortcomings with the prior art methods for attaching a right angle milling head to a horizontal boring machine are overcome.